I’m not in the Seattle area, so can’t answer regarding the specific utility.Is anyone else on here a customer of Seattle City Light, or really into the bi-directional charging stuff? A few years ago, we installed solar panels. As part of the project, we also switched to gas on-demand water hearing, a whole house electric heat pump and got an induction range. We also have a 2019 Kia Niro PHEV. For anyone interested in electrification, my advice would be to switch out your 'plant' and use it for a year before you try to size a solar system. We went from covering 102% of our projected annual load to just about 89%. Still great, and we're happy, but adding a 2nd BEV or whatever you call the car with the Harvester option (EREV?), will likely take us down another 20% or so?
Anyway, I've always been interested in the whole house battery back-up. It's actually kind of silly in Seattle since the area that I'm in rarely has outages and most of our power comes from firm, clear hydropower. Still, there's always the BIG ONE that's looming on the time horizon and who know what the future holds when our robot overlords finally rise up and takeover. So, the appeal of a giant battery on wheels to give me DAYS of back-up over the exorbitant cost of home batteries is great... but my understanding is that you need some kind of battery on site to provide the 'reservoir pressure' to your own little microgrid. At some point I'll need a battery if I want my Scout to back-up my house.
I've priced out a couple of options, but when we got down to it, the big problem was siting the home battery. If we do it outside our house, then we've got the eyesore of a mini-fridge we have to look at in the back yard. If we do it in our garage (which is right below our living room), I'll need to switch out the drywall from 1/4 to 5/8 to meet fire code. That project alone is close to 8K.
I'd love to connect with folks in the Seattle area who might be into gaming this out and talking about different concerns or ideas.
However, I’ve installed more than a few solar systems. Two for myself and several for others, grid-tied and off-grid.
Without knowing all of your intentions, here’s a broad overview:
You don’t need a secondary battery to make use of your BEV. You do need some mechanism for pulling power from the BEV. That can be a bidirectional charging setup, which can get expensive. It can be using a 240 V outlet in the vehicle (the Lightning has this, for example). The Lightning’s bidirectional output is limited to 40 Amps, 240 Volts, or 9.6 kW. The Lightning’s 240 V outlet in the bed is limited to 30 Amps, 240 Volts, or 7.2 kW. This is going to be similar for other vehicles. If you use the 240 V outlet, it’ll be treated as a generator for the purposes of connecting to the house. An electrician can help with that set up. It’s not (necessarily) automated. The bidirectional setup is automated only if the vehicle is plugged in when the power goes out.
For cost savings and reduction in emissions, a whole-home battery is the quickest and cheapest way to go. No solar. Just a battery that’s large enough to cover four to six hours (or more) of usage. This helps flatten out the duck curve (peak demand from about 3:00 PM to about 8:00 PM, depending on the specifics of your community). You would set your battery to recharge from the grid during the lowest cost time of day. If your utility charges extra for use during the peak demand, a battery can quickly reduce your monthly bills. You can use the BEV for this in one of the two ways I mentioned above. If you use the bidirectional option, you’ll need to have some kind of non-outage trigger to tell the BEV to take over during the specified times. I don’t have a bidirectional system, so I don’t know if they come with that kind of time-based trigger. I would imagine they do. If you’re using the 240 V plug, this is a manual action and you just have to remember to plug in, switch the breaker, and then undo all of it when you need to.
With solar, you can use the solar either independently, with a whole-home battery, with the BEV, or with all three. You can also get an EVSE that uses your excess solar to charge your BEV, if it’s home during the times when you have excess solar. This is a more costly solution, but it does offer some benefits not attainable without solar, especially if paired with a battery. Specifically, solar+battery offers longer-term cost savings and longer-term outage resiliency.